$.fn.smartFloat = function() {
  var position = function(element) {
    var top = element.position().top,
      pos = element.css("position");
    $(window).scroll(function() {
      var scrolls = $(this).scrollTop();
      if (scrolls > top) {
        if (window.XMLHttpRequest) {
          element.css({
            position: "fixed",
            top: '0'
          });
        } else {
          element.css({
            top: scrolls
          });
        }
      } else {
        element.css({
          position: pos,
          top: top
        });
      }
    });
  };
  return $(this).each(function() {
    position($(this));
  });
};